For the treatment of various diseases, it is often helpful to enhance the patient's natural blood circulation. It is particularly desirable to promote blood circulation in the treatment of various ischemic diseases which occur in the extremities or limbs of the body. By artificially promoting blood circulation, the development of ischemic lesions on a patient's extremities can be curtailed and in fact even small gangrenous lesions may be healed or arrested.
To artificially enhance the patient's natural blood flow through an extremity, devices have been utilized which apply and remove pressure from at least a portion of the patient's extremity. For example, the patient's extremity can be enclosed in an air bladder or air bag which can be inflated to apply pressure on the extremity and deflated to remove pressure from the extremity. Through the application of pressure, blood can be forced into the extremity.
In order to function properly, expansion of the air bag must be restricted or controlled so the application of pressure on the extremity can be controlled.
As set forth in my earlier U.S. Pat. Nos. 3,961,625, 4,269,175 and 4,343,362, it is desirable to restrict the volume of expansion of the air bag as much as possible while still enabling unrestricted controlled fluid flow through the air bag, to control the compression and decompression of the patient's extremity, and to this end a rigid retaining means structure was preferred to enclose the air bag. Since the rigid structure was not convenient in all cases, it was suggested that a flexible outer retaining garment be used to control the air bag.
The restriction of air flow through the air bag may be a problem when a rigid outer retaining structure is employed to confine the air bag in close proximity aroung the patient's extremity. However, the problem becomes magnified when a flexible outer retaining garment is employed. The efficiency of the system was decreased when using a flexible outer retaining garment because application of pressure to the extremity is delayed until after the air bag fully distends the flexible outer retaining garment, and if the flexible outer retaining garment is adapted to closely constrain the air bag in an attempt to improve efficiency, fluid flow through the air bag becomes greatly restricted and obstructed.